Sunday, May 30, 2010

California dreamin'...of help from Vetiver!

California's myriad problems, from tempestuous wildfires to torrential rains, scream for relief. And Vetiver's been tried by the most austere conditions and been found true--in California, in the mid-1990s. Today Wolfram Alderson (Wolfram's World) dug up the history:

Worst case scenario provided for Vetiver grass planting at California State Polytechnic University, Pomona.

Vetiver grass was given an opportunity to demonstrate its tolerance of poor soil and environmental conditions in a "worst case scenario" at Land Lab, an 340-acre environmental study area at California State Polytechnic University, Pomona. During the summer of 1994, 44 Vetiver plants were installed along a cut face slope leading up to the Land Lab Information Center.

Vetiver was among plant materials included in a revegetation project implemented by the Casa Colina Horticulture Therapy and Training Program, a Pomona-based program that provides employment and training for people with disabilities.

The goal of the revegetation project was to restore the ability of the native California Black Walnut trees on the site to seed new generations of tree saplings. Before the project, mostly old growth trees and very few young trees had survived unfavorable conditions that had previously included overgrazing, construction activities, a canopy of invasive exotic weeds, and few surviving native or understory plants. Soil conditions were very poor and heavy erosion and landslides were prevalent.

Only "moondust and shale" soil was left after construction of a road leading to the Land Lab Information Center. Topsoil and more than ten feet of earth were removed, leaving a dry, shale-pocked substance entirely devoid of organic matter. During the summer, wind and sun pummeled lifeless dust and rock that crumbled and cascaded down the slope face onto the asphalt roadway. In winter months, rains turned the material into a gray mud that frequently slipped downhill in mudslides or simply washed down the driveway in a milky flow. As a general reference, temperatures in the Los Angeles area range from 28F to 110F, with a mean of 64.4 F. Normal Los Angeles rainfall is 14.68 inches/year. Vetiver can survive with as little as 12 inches of annual rain, but average rainfall of 27.5 inches is preferable.

When the 4‰ container-sized Vetiver was planted, portable Rainbird sprinklers provided some irrigation during the initial months following planting. However, frequent waterline breaks and other challenges starved the plants for water and attention during the first year. No irrigation has occurred at all since the sporadic watering of the first year. After a three-year revegetation period, project funding was discontinued and site maintenance was abandoned.

Remarkably, as of December 1999, 90% of the Vetiver planted at the site survived the soil, the blazing sun, the afternoon winds, and even a large population of voracious rabbits that get its water and food from the vegetation. Although the Vetiver that remains would clearly look happier if they were to get a little more water, it's amazing that Vetiver survived when other native plantings did not. When Vetiver is stressed, it "hunkers down," growing lower and exhibiting more dry bades. But, as you seen here and in other Southern California Vetiver images, Vetiver has survived here while native sages and plants considered to be more drought tolerant have not. Quite an accomplishment for this simple little clump of tropical grass!

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